KMSP - It’s called the Great American Total Solar Eclipse for a reason, because it’s a once in a lifetime opportunity. In just 2 weeks, during the late morning and early afternoon of Monday August 21, the United States will get its first total solar eclipse in decades. But Minnesota won’t be in the path of totality, so why should we care? What does “path of totality” even mean? What is a solar eclipse? Well, here are some facts and figures to help you get excited about science.

Earth has roughly 2 solar eclipses a year on average

A solar eclipse happens when the moon passes in front of the sun casting a shadow onto the Earth as it orbits around us. This happens roughly twice a year. It only happens that often because the moon revolves around the Earth on a constantly changing angle. It’s also roughly the same size in our sky as the sun, giving it a much smaller chance of “getting in the way.” If it were bigger, it would happen far more often. You combine all of those factors, along with a solar eclipse only being able to take place in the daytime, and you will only see a couple a year on average.

Most eclipses are not total

There are actually 4 types of eclipses. Partial eclipses are when the moon only crosses part of the sun. They make up about 35 percent of all eclipses. This is the type of eclipse that Minnesotans will see from our vantage point later this month. 32 percent of eclipses are annular, meaning that the moon passes directly over the sun, but is too far away from Earth to cover it completely (Remember that the moon’s orbit isn’t perfectly circular so there are times the moon is closer to the Earth than other times). This will give the sun a ring appearance because the outer edge of the sun is still seen. 28 percent are total eclipses, when the moon completely blocks out the sun in a small path on the Earth. The final 5 percent are some combination of the 3, transitioning from one to the other.

Total eclipses are RARE in the U.S.

A total eclipse is only visible from a narrow path along the Earth which makes it rare to see to begin with. But for that small path to come to you is even more rare. At any given point in the world, you will see a total solar eclipse in your location roughly every 150 years. But that can vary widely. For example, there are areas of Missouri and Illinois that will see the total eclipse this year, and another one just 7 years from now. But there are parts of the country that haven’t seen one in more than 500 years. Parts of southern Minnesota are actually on that list.

Here’s a glimpse at just how rare they are. The last time the U.S. experienced one was Hawaii in 1991. For the continental United States, it was 1979, and only the Pacific Northwest got to view it. The last time a total solar eclipse passed across the entire continental U.S. was nearly a hundred years ago, but it also traveled over parts of eastern Asia. This total eclipse is ONLY visible from the United States, which is the first time that has happened since our great country was born in 1776.

How to view the eclipse

While Minnesota won’t experience totality, anywhere from 70 to 90 percent of the sun will be covered. But you can’t look at it directly, even with that much of the sun blocked, or you will damage your eyes. No, your standard sunglasses won’t work either; you will need to get some special solar glasses. These are usually pretty cheap (a couple bucks each), but will likely climb in price the closer we get to the event. But beware of fakes! Your solar glasses must have the ISO symbol and code on it for them to protect your eyes the way they should. If you don’t want to mess with buying them, there are some libraries that have free ones to give away while they last. To find out if your library is one of them, you can check out this link… http://www.starnetlibraries.org/2017eclipse/registered-libraries-map/

If you don’t want to even bother with the glasses at all, there are even easier ways to view. Just take a pencil and poke a hole in a piece of paper. Walk outside during the event and cast a shadow with that paper. The portion of the sun that’s covered will show up on the ground giving you a crescent shaped shadow.

When is the next one?

If you’re busy that day, or it’s cloudy, or you just don’t care right now, the good news is you’ll get another shot soon. The next total solar eclipse to cross the U.S. will happen on April 8, 2024. But, Minnesota will once again be in the partial eclipse spot as the path of totality goes from Texas to Maine. As for Minnesota, we will drop into darkness from the path of totality in a total eclipse before the end of the century, but you have to wait until 2099.